Quantification of Mitral Regurgitation in Mitral Valve Prolapse by 3D Vena Contracta Area: Derived Cut-off Values and Comparison with 2D Multiparametric Approach.

Background Echocardiographic grading of mitral regurgitation (MR) in mitral valve prolapse (MVP) is challenging. 3D vena contracta area (3D VCA) has been proposed as valuable method. However, data defining the cut-off values of severity and validation in the subset of patients with MVP are scarce. The aim of this study was to validate the 3D VCA by 3D transesophageal color-Doppler echocardiography (3D-TEE) in patients with MVP and to define the cut-off values of severity grading. The secondary aim was to compare 3D VCA to the EROA-PISA method. Methods 1138 patients with at least moderate MR who underwent TEE were included. 3D VCA was measured, the cut-off value and area under the curve (AUC) for the prediction of severe MR were estimated by ROC curve using guideline-suggested multiparametric approach as reference standard. In a subgroup of patients, 3D regurgitant volume (3D RV) and 3D fraction (3D RF) were calculated from mitral and left ventricular outflow tract stroke volumes to further validate 3D VCA against a 3D volumetric reference standard. Results The optimal 3D VCA cut-off value for predicting severe MR was 0.45cm2 (specificity 0.87; sensitivity 0.90) with an AUC of 0.95 using multiparametric approach as reference. 3D VCA had a good linear correlation with EROA-PISA (r = 0.62, p<0.05) with larger values compared to EROA-PISA (0.63 cm2 vs 0.44cm2, p<0.05). A cut-off of 0.50cm2 (AUC of 0.84, sensitivity 0.78, specificity 0.78) predicts an EROA-PISA of 0.40cm2. 3D VCA had a good linear correlation with 3D RVOL (r= 0.56, p<0.01), with an AUC of 0.86 to predict a 3D RF > 50%. Conclusions The present study suggests 0.45 cm2 as the best cut-off value of 3D VCA to define severe MR in patients with MVP, showing an optimal agreement with the reference standard multiparametric approach and 3D RV.